In large bowl, whisk together dressing ingredients until blended; set aside. In medium saucepan, cook potatoes, covered, in 2 inches boiling water, about 10 minutes or until just tender; drain thoroughly, then shake potatoes over low heat 1 to 2 minutes to dry thoroughly. Add potatoes, while still warm, to dressing; toss to coat. Add celery, eggs, capers, and salt; toss gently to combine. Season with pepper, as desired. Serve on lettuce-lined salad plates, if desired.